The Arizona STEM Acceleration Project
Modeling Changes to Stomach Volume
Modeling Changes to Stomach Volume Over the Course of a Single Day
A 10-12 Grade STEM Lesson
Joshua Farr
November 2023
Notes for Teachers
List of Materials
Arizona Science Standards
HS.L2 Organisms require a supply of energy and materials for which they often depend on.
Essential HS.L2U1.19 Develop and use models that show how changes in the transfer of matter and energy within an ecosystem and interactions between species may affect organisms and their environment.
Science & Engineering Practices:
Crosscutting concepts highlighted in this lesson involve:
11-12.SL.1 Initiate and participate effectively in a range of collaborative discussions (one‐on‐ one, in groups, and teacher‐led) with diverse partners on grades 11–12 topics, texts, and issues, building on others’ ideas and expressing their own clearly and persuasively. Propel conversations by posing and responding to questions that probe reasoning and evidence; ensure a hearing for a full range of positions on a topic or issue; clarify, verify, or challenge ideas and conclusions; and promote divergent and creative perspectives.
11-12.SL.4 Present information, findings, and supporting evidence in an organized, developed style appropriate to purpose, audience, and task, allowing listeners to follow the speaker's line of reasoning, message, and any alternative perspectives.
Mathematical Practices:
MP.4 Model with mathematics.
Objective(s):
Identify the structure and function of the human stomach. Model the changes in the stomach volume throughout a day with balloons while graphing the changes over time. Develop graphical analysis skills while building stories to explain the changes in the observed graphs.
Students will need to listen to one another, critique their graphs and models, and extend their thinking to analyze diverse dieting options that many people find normal (3 “square meals a day” versus intermittent snacking, intermittent fasting, or enjoying a large “holiday meal”. The objective is also to have fun with the stories, connect to their own lives, and practice their storytelling skills while connecting to data.
Extension activities could involve illustrating stories described above in a series of sketches such as a one page comic, a multi-page story, or a flip book. Researched topics and Radiolab are additional suggested options for expansion activities if interest is high (or lacking for that matter!).
Agenda (50-60 minutes)
Where is the stomach located (identify body cavity & use directional terms)?
Based on the stomach structure, how does the stomach function?
Model expansion and contraction of the stomach muscles with balloons. Graph the change over time and explain the graph.
Establish a graph that represents your day on food consumption and model it with balloons and on a graph.
Share your story with your peers and build a library of different stories.
Lesson can be contracted or expanded based on the time provided that day (pun intended).
How does the system change over time?
Throughout the day, we get hungry, eat, and digest. Our stomach has the ability to expand and contract based on the structure being made of layers of muscle tissue (muscles shorten when contracted). Based on one's diet, the stomach may expand a lot or a little, quickly or slowly depending on eating habits and frequency of consumption. Using a balloon and storytelling, students will model this process and graph the results.
Identify the stomach, location, and structure
Introduce the stomach location, connect back to body cavities (thoracic and abdominal) while using directional terminology
Expansion and contraction: our balloon is a model for our stomach and inflation/deflation the passage of time.
Set up graphs on whiteboards, ea. student
Explain the x axis is time
Explain the y axis as volume
Inflate the balloon!
What can this graph tell us?
This may be a more typical “3 square meals a day” sort of graph
The balloon (stomach) is not completely empty when we start but rises exponentially before declining
There’s a gap of time between the next inflation (meal)
This may be an easier graph to understand for the students and may be the first graph that you help create with the students
We also realize that time on the x-axis is very important! This could be three bites of food or three separate meals across 24 hours! Get them to be analytical about time.
What can this graph tell us?
First, the balloon (or stomach) was not completely empty at the start!
Volume increased over time and then leveled out but time did not stop so it continued along a flat line
Volume increased again then leveled out
Volume increased one more time before declining rapidly
At the end, the volume is not completely empty
What can this graph tell us?
Perhaps this would represent a “snacking” situation throughout the day?
The balloon (stomach) volume doesn’t get very “full” all at one time
Is this a healthier approach? Are there costs or benefits from this sort of diet?
Rapid fire question assessment
What did you notice? Ask the following questions:
1. Where did you start on the graph? Was the balloon fully empty at the start?
2. Were there peaks and valleys on the graph? If they are blunt pauses what does that imply about time?
Hands-On Activity Instructions
In a group of 2-4, have one partner inflate their balloon. Suggest they be creative with it. The other partner(s) will graph what happens to the balloon over time. When done, switch who is doing what. Teacher walks around to provide support.
Materials required:
Circle back to our stomach!
Each group will now model the change in stomach volume over the course of a day (24 hours).
Select one member of the team to pretend their stomach is the balloon. What was their food intake like yesterday? Inflate it while your buddy graphs.
Differentiation!
As the teacher walks the room, search for different examples. Be on the lookout for groups that model:
Be sensitive to the fact that not all students may have the same opportunities for access to food.
Different groups produce different results
Extension/Enrichment
Grab your top 3 or 4 scenarios and collect those whiteboards.
Put those whiteboards around the room or up front on the main whiteboard ledge as “stations” that students must rotate around to.
Provide notebook pages where students will sketch and then write out the story for the graph.
SKETCH OF GRAPH
Story composed of 3-4 sentences that tells the story of the stomach throughout the prior 24 hour period
Which story represents your typical food consumption? Take a survey and see what conversation gets started!
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How do we assess our work?
Assessment
Test their understanding:
ELA Assessment
Tell the story of a person's stomach volume over the course of day. Illustrate the process and include graphs in the illustration process that correlate to the expansion and contraction of the stomach volume. Explain if you think there are better or healthier ways to eat, a preferred diet, or method for keeping the body and the stomach healthy and functioning as normal.
Additional Materials
Materials
Optional items